High-power, continuous-wave, single-frequency, all-periodically-poled, near-infrared source

Abstract

We report a high-power, single-frequency, continuous-wave (cw) source tunable across 775-807 nm in the near-infrared, based on internal second harmonic generation (SHG) of a cw singly-resonant optical parametric oscillator (OPO) pumped by a Yb-fiber laser. The compact, all-periodically-poled source employs a 48-mm-long, multigrating MgO doped periodically poled lithium niobate (MgO:PPLN) crystal for the OPO and a 30-mm-long, fan-out grating MgO-doped stoichiometric periodically poled lithium tantalate (MgO:sPPLT) crystal for intracavity SHG, providing as much as 3.7 W of near-infrared power at 793 nm, together with 4 W of idler power at 3232 nm, at an overall extraction efficiency of 28%. Further, the cw OPO is tunable across 3125-3396 nm in the idler, providing as much as 4.3 W at 3133 nm with >3.8 W over 77% of the tuning range together with >3 W of near-infrared power across 56% of SHG tuning range, in high-spatial beam-quality with M2<1.4. The SHG output has an instantaneous linewidth of 8.5 MHz and exhibits a passive power stability better than 3.5% rms over more than 1 min.

High-power PPMgLN-based optical parametric oscillator pumped by a linearly polarized, semi-fiber-coupled acousto-optic Q-switched fiber master oscillator power amplifier

“…According to these requirements, fiber lasers are supposed to be the best candidates among all the OPO pump sources due to their compactness, robustness, excellent beam quality, and simple thermal management schemes [3]. Therefore, fiber-laser-pumped OPOs have been extensively investigated from continuous wave (CW) to ultrashort pulsed operation schemes [4][5][6][7][8][9][10][11][12][13]. Among all these pump sources, fiber lasers with tens to hundreds of nanoseconds are particularly useful in outdoor applications for both environmental monitoring and missile countermeasures because simple linear cavities are applicable to such pump sources converting the pump power to idler output efficiently during each pulse with peak power higher than the CW OPOs and dimensions smaller than the synchronously pumped OPOs.…”

Theoretical analysis of a continuous-wave 323 nm laser generated by a singly resonant optical parametric oscillator with intracavity sum-frequency generation

“…With the rapid development and maturity of tunable single frequency Yb-doped fiber lasers at 1064 nm and periodically poled crystals (PP-crystals, such as periodically poled MgO-doped stoichiometric LiTaO 3 (MgO:sPPLT) and MgO:PPLN), a tunable CW visible to UV radiation, which is inaccessible to conventional laser sources, can be obtained through nonlinear frequency conversion. The intracavity SHG of the resonant signal [9][10][11][12][13] or intracavity SFG between the pump and the signal in the singly resonant optical parametric oscillator (SRO) [14][15][16][17] are recognized as attractive approaches to generate tunable radiation from visible to UV. The intracavity SFG can provide shorter wavelengths than the intracavity SHG in the same SROs, thus, it is preferred for generating CW single frequency laser radiations at 646 and 323 nm.…”

Amplified random fiber laser-pumped mid-infrared optical parametric oscillator

“…Many applications, such as environmental monitoring, high-resolution molecular spectroscopy, and infrared countermeasures, require mid-infrared (MIR) sources operating in the 3-5 μm wavelength range [1][2][3] . Optical parametric oscillators [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] (OPOs), especially fiber laserpumped MgO: PPLN OPOs [10][11][12][13][14][15][16][17][18][19][20] , provide an effective approach to generate MIR lasers for their compact volume, electrical operation, and high conversion efficiency, which have attracted the interest of many researchers. In 2014, we reported the highest continuous-wave (CW) output power of 34.2 W at 3.35 μm from an MgO: PPLN OPO, which was pumped by a homemade quasi-single-frequency (SF) Yb-doped fiber laser [21] .…”